J/AJ/155/183ivo://CDS.VizieR/J/AJ/155/183doi:10.26093/cds/vizier.51550183CDSSalinas R.Pajkos M.A.Vivas A.K.Strader J.Contreras Ramos R.2020-01-31T11:57:45Z2018-11-27T13:26:36ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frmagellanic-cloudsglobular-star-clustersvariable-starsvisible-astronomysloan-photometryastronomical-object-identificationIntermediate-age (IA) star clusters in the Large Magellanic Cloud (LMC) present extended main-sequence turn-offs (MSTO) that have been attributed to either multiple stellar populations or an effect of stellar rotation. Recently it has been proposed that these extended main sequences can also be produced by ill-characterized stellar variability. Here we present Gemini-S/Gemini Multi-Object Spectrometer (GMOS) time series observations of the IA cluster NGC 1846. Using differential image analysis, we identified 73 new variable stars, with 55 of those being of the Delta Scuti type, that is, pulsating variables close the MSTO for the cluster age. Considering completeness and background contamination effects, we estimate the number of {delta} Sct belonging to the cluster between 40 and 60 members, although this number is based on the detection of a single {delta} Sct within the cluster half-light radius. This amount of variable stars at the MSTO level will not produce significant broadening of the MSTO, albeit higher-resolution imaging will be needed to rule out variable stars as a major contributor to the extended MSTO phenomenon. Though modest, this amount of {delta} Sct makes NGC 1846 the star cluster with the highest number of these variables ever discovered. Lastly, our results present a cautionary tale about the adequacy of shallow variability surveys in the LMC (like OGLE) to derive properties of its {delta} Sct population.2018AJ....155..183Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/155/183CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AcA/53/93 : OGLE RR Lyrae in LMC (Soszynski+, 2003)J/AcA/59/1 : VI light curves of LMC RR Lyrae stars (Soszynski+, 2009)J/AcA/59/239 : VI light curves of LMC long-period variablesJ/AcA/60/1 : VI light curves of LMC delta Scuti stars (Poleski+, 2010)J/AJ/145/160 : Variables in LMC globular clusters. III. ReticulumJ/MNRAS/430/676 : Massive clusters in the LMC (Baumgardt+, 2013)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/155/183https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/155/183http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/155/183https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/155/183https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/155/183http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/155/183GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/155/183/table1 (Positions, mean magnitudes, r amplitudes, periods and classification for all of the variables discovered in the NGC 1846 field)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/155/183/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/155/183/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/155/183/table1?GETtext/xml+votable180.050000true76.79192083-67.476208330.0055555555555555566/33124https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/155/183?format=asciiOpticaldefaultJ/AJ/155/183/table1Positions, mean magnitudes, r amplitudes, periods and classification for all of the variables discovered in the NGC 1846 fieldrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDVariable star identifier in NGC 1846 field (VNN)meta.id;meta.maincharn_ID[*] Denotes a note on the individual source in the Appendix of this paper (see appen.dat file)meta.notecharRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.maingmagmean[18.78/24.58]? Mean g band magnitudemagphot.mag;em.opt.Bfloatnullablermagmean[18.86/24.44]? Mean r band magnitudemagphot.mag;em.opt.RfloatnullablerAmp[0.01/0.8]? r band amplitudemagsrc.var.amplitudefloatnullableu_rAmp[:] Uncertainty flag on rAmpmeta.code.errorcharl_Per[>] Lower limit flag on Permeta.code.errorcharPer[0.038/0.2] Perioddtime.periodfloatTypeClassification (1)meta.code.classcharCICross identification with OGLEmeta.id.crosscharSimbadSimbad column added by the CDSmeta.ref.urlcharJ/AJ/155/183/appenNotes on Some Individual VariablesIDVariable star identifier in NGC 1846 field (VNN)meta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNoteText of the notemeta.note